MODELING 1,3-DICHLOROPROPENE FUMIGANT VOLATILIZATION WITH VAPOR-PHASE ADVECTION IN THE SOIL-PROFILE

The simulation model LEACHP, a pesticide version of LEACHM, was modified to include air flow driven by barometric pressure change at the soil surface, resulting in LEACHV, a model describing volatile-phase transport. LEACHV provides explicit simulation of vapor-phase advection. Development of LEACHV was aided by using input data appropriate to the conditions of an Imperial Valley field experiment in which the volatilization flux of 1,3-dichloropropene (1,3-D) was measured and by comparing simulated and measured data at various stages of development. Sensitivity analysis was then conducted for the primary parameters in LEACHV. In a subsequent comparison of simulated and measured volatilization for a Salinas Valley field, without any curve fitting and parameter manipulation, the LEACHV simulation produced the same general pattern as the measurement in response to changes in barometric pressure.